Previous disclosures, such as U.S. Pat. No. 4,976,799 and U.S. Pat. No. 5,137,539 have described methods and apparatus for achieving controlled shrinkage of collagen tissue. These prior inventions have applications to collagen shrinkage in many parts of the body and describe specific references to the cosmetic and therapeutic contraction of collagen connective tissue within the skin. In the early 1980's it was found that by matching appropriate laser exposure parameters with these conditions, one had a novel process for the nondestructive thermal modification of collagen connective tissue within the human body to provide beneficial changes. The first clinical application of the process was for the non-destructive modification of the radius of curvature of the cornea of the eye to correct refractive errors, such as myopia, hyperopia, astigmatism and presbyopia. New studies of this process for the previously unobtainable tightening of the tympanic membrane or ear drum for one type of deafness have been made.
CO2 laser resurfacing is not a new technique. CO2 lasers have been used for several years, but regular continuous wave CO2 lasers can cause scarring due to the tissue destruction caused as heat as conducted to adjacent tissue. Even superpulse CO2 lasers produce excessive thermal damage. The Ultrapulse CO2 laser introduced by Coherent, Inc. is an attempt to assuage these drawbacks by offering a high energy, short duration pulse waveform limiting the damage to less than 50 microns allowing a char-free, layer by layer vaporization of the skin tissue.
All of the foregoing procedures depend for their success upon primary damage and the reparative potential induced by the inflammatory process in the tissue. Associated with inflammation are, of course, the four cardinal signs of inflammation of rubor (hyperemia), calor (thermal response), dolor (pain), and tumor or edema or swelling. Coincident with these manifestations is the risk of reduced resistance to infection. One must not forget that these collateral effects accompany a cosmetic enhancement procedure and, for the most part, are not associated with a therapeutic procedure. Therefore, the development of a more efficacious method would be beneficial in this regard.
U.S. Pat. Nos. 4,976,709, 5,137,530, 5,304,169, 5,374,265, 5,484,432 issued to Sand, disclose a method and apparatus for controlled thermal shrinkage of collagen fibers in the cornea using light at wavelengths between 1.8 and 2.55 microns. However strong absorption of the laser energy by water limits the penetration depth to the most superficial layers of skin.
The CoolTouch™ 130 laser system by CoolTouch Corp of Auburn, Calif., was first introduced at the Beverly Hills Eyelid Symposium in 1995. It utilizes a laser at a wavelength of 1.32 microns to cause thermally mediated skin treatment. In this device the treatment energy is targeted at the surface of the skin with in depth optical heating of the epidermis, papillary dermis, and upper reticular dermis. The energy is primarily absorbed in tissue water with a skin absorption coefficient of 1.4 cm−1, corresponding to an absorption depth of 0.71 cm. Scattering of the 1.32 micron wavelength light by skin microstructures alters the distribution of light from an exponential attenuation to a more complex distribution, which has much faster attenuation approximating an absorption depth of 0.1 cm. Most of the energy is absorbed in the first 250 microns of tissue. To prevent overheating of the epidermis pulsed cryogen spray precooling is used. U.S. Pat. No. 5,814,040, issued Sep. 29, 1998, describes a dynamic cooling method utilizing pulsed cryogen spray precooling. Skin treated with this device has improved texture and a reduction in wrinkles and scarring due to the long term renewal of dermal collagen without significant skin surface wounding.
U.S. Pat. No. 5,810,801 teaches a method and apparatus for treating a wrinkle in skin by targeting tissue at a level between 100 microns and 1.2 millimeters below the surface, to thermally injure collagen without erythema, by using light at wavelengths between 1.3 and 1.8 microns. The parameters of the invention are such that the radiation is maximally absorbed in the targeted region. The invention offers a detailed description of targeting the 100 micron to 1.2 mm region by utilization of a lens to focus the treatment energy to a depth of 750 microns below the surface. Because of the high scattering and absorption coefficients, precooling is utilized to prevent excess heat build up in the epidermis when targeting the region of 100 microns to 1.2 mm below the surface. The wavelength range of use is 1.3 microns to 1.8 microns in order to avoid the wavelength range of Sand. However the wavelength range of 1.4 to 1.54 microns and the range between 2.06 and 2.2 microns have identical effective attenuation coefficients in skin. Also the range from 1.15 to 1.32 microns has a fairly uniform effective attenuation coefficient in skin of about 6 to 7 cm−1. The effective attenuation length in skin for the range of wavelengths of 1.3 to 1.8 microns varies from 6 cm−1 at 1.3 microns to 52 cm−1 microns, corresponding to penetration depths in skin of 200 microns to 2 millimeters. Specific laser and cooling parameters are selected so as to avoid erythema and achieve improvement in wrinkles as the long term result of a new collagen formation following treatment.
Mucini et al. reported effective dermal remodeling using a 980 nm diode laser with a spherical handpiece which focused irradiation into the dermis avoiding the high scattering and absorption characteristic of longer wavelengths. The device requires a small lens of a few millimeters in contact with skin and results in a slow procedure when used for facial areas.
Ross et al., reported the use of an Erbium:YAG laser operating at a wavelength of 1.54 microns fired in a multiple pulsed mode has been described for eliciting changes in photodamaged skin A chilled lens in contact with skin at the treatment site was used in an attempt to spare the epidermis. Treatment occurred during a period of several seconds with a sequence of cooling and heating with the laser and handpiece. At 1.54 microns the optical penetration depth 0.55 mm and the authors reported that the surface must be chilled before the laser exposure requiring a complex method of cooling and laser exposure. The authors state that a more superficial thermal injury may be needed than could be achieved, and that there are increased patient risks because it would demand more accurate and precise control of heating and cooling.
Bjerring et al, reported the use of a visible light laser, operating at 585 nm wavelength, to initiate collagenesis following interaction of laser energy with small blood vessels in skin.
As many as 700 million people worldwide suffer from onychomycosis or toenail fungal infections. There are many systemic, topical and herbal treatments available to treat this disease but none are truly efficacious and several have severe potential side effects. A need exists for a better cure for this widespread disease.
Optical and laser treatment of toenail fungus has been known for many years. In particular, UV light in the 100-400 nm range has proven to be able to inactivate many pathogens including the ones responsible for onychomycosis in non-thermal dosages. Unfortunately UV light has difficulty penetrating the toenail and can cause side effects in the dermis. UV light is not considered to be a successful treatment modality despite a great deal of research.
U.S. Pat. No. 6,723,090, issued Apr. 20, 2004 to Altshuler et al., U.S. Pat. No. 7,220,254, issued May 22, 2007 to Altshuler et al., US Publication No. 2006/0212098, published Sep. 21, 2006 to Demetriou et al., Non-patent publication “Laser treatment for toenail fungus”, Proc. of SPIE Vol. 7161 published 2009 by Harris et al. and others have proposed using infrared radiation to thermally inactivate toenail fungus. Infrared radiation penetrates the toenail much better than UV and it has been shown that the fungus can be inactivated by raising the temperature of the pathogen to about 50° C. The problem associated with this method is that achieving the inactivation temperature in the nail bed risks damaging the surrounding dermal tissue, especially the matrix where the nail actually grows. In addition this prior art allows the use of infrared radiation with high hemoglobin absorption. Hemoglobin absorbing wavelengths can coagulate capillaries in the proximal fold and permanently damage the toenail.
U.S. Pat. No. 6,723,090, issued Apr. 20, 2004 to Altshuler et al., U.S. Pat. No. 7,220,254, issued May 22, 2007 to Altshuler et al. propose to use a cooling modality to protect the toenail during infrared laser irradiation to target the nail bed and he suggests that a pulsed laser may be superior to a continuous one.
US Publication No. 2006/0212098, published Sep. 21, 2006 to Demetriou et al. suggests the use of pulsed cryogen cooling, which is also described in U.S. Pat. No. 5,814,040, issued Sep. 29, 1998 to Nelson et al., to protect the toe from excessive heating and to use the process of selective photothermolysis, which is disclosed in non-patent publication “Selective Photothermolysis: Precise Microsurgery by Selective Absorption of Pulsed Radiation”, published on Science, 220:524-527, 1983 by Anderson et al., to choose the correct pulse length to match the thermal properties of the fungus itself. Methods taught respectively in U.S. patent '090, '254 to Altshuler et al. and US Publication '098 by Demetriou et al. all require relatively high target temperatures that can damage the matrix and teach to cool only the surrounding tissue. The above-mentioned methods may cause permanent damage to sensitive areas.
U.S. Pat. No. 6,090,788, issued Jul. 18, 2000 to Lurie teaches that light-absorbing substances may be considered to induce and enhance selective photothermal damage. The problem and shortcoming with this method is the difficulty in getting the substance infused to the proper areas and the high temperatures required to inactivate the microbe. Damage to the surrounding tissue is likely to happen by using this method.
Non-patent publication “Method for disruption and re-canalization of atherosclerotic plaques in coronary vessels with photothermal bubbles generated around gold nanoparticles”, published on Lasers Surg Med, 2009. 41(3): p. 240-7 by Lukianova-Hleb, E. Y., A. G. Mrochek, and D. O. proposes a non-thermal mechanical and localized removal of plaque tissue with photothermal microbubbles—PTMB to re-canalize occluded arteries without collateral damage using gold nano particles—GNP. It also teaches that users can induce non-thermal damage to locally remove unwanted tissue by producing PTMB using GNP as a catalyzer. This method however has not been proven to be efficient enough to be practical in removing large volumes of plaque buildup.
Non-patent publication “Laser surgery of port wine stains using local vacuum pressure: Changes in skin morphology and optical properties (Part I)”, published on Lasers Surg Med, 2007. 39(2): p. 108-17 by Childers et al. proposes that mild vacuum pressures applied to the skin surface causes changes in morphology and its optical properties. These changes may be used for more efficient photothermolysis of small Port Wine Stain blood vessels. The vacuum suggested by Childers et al. however works primarily on blood vessels in the dermis.